Radio receiving system



g- 1929- E. F. w. ALEXANDERSON 1,723,907

RADIO RECEIVING SYSTEM Filed May 11, 1923 2 Sheets-Sheet 1 Fig.1.

\NJ IO Aumo TUNER g m 7 W l m l l l llllmnm l2 Fig.2.

RECEIVER InVantor: Ernst FTWAlexanderson His Att o fi s? Aug. 6, 1929. E. F. w. ALEXANDERSON RADIO RECEIVING SYSTEM Filed May- 11, 1923 2 Sheets-Sheet Irv/cantor Ernst, FIwAlexahder-son, by His Attorn ey.

Patented Aug. 6, 1929.

ERNST F. 'W. ALEXANDERSON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

RADIO RECEIVING SYSTEM.

Application filed May 11,

My present invention relates to systems for receiving high frequency radio signals, and more particularly to systems of this nature having a high degree of selectivity.

My present application is a continuation in part of my prior application, Serial No. 511,127, filed October 28, 1921, Patent No. 1,491,372.

Selectivity in radio reception in the past has only taken into account the frequency of the signaling wave and the direction of wave motion. By means of these two factors it is possible to eliminate to a large extent interference from undesired stations of different wave length, or stations having approximately the same wave length, which are located in a different direction from the receiving station than the station from which signals are to be received. By means of these selective features it is also possible to eliminate to a large extent the effect of static disturbances, particularly those which are traveling in a different direction than the direc tion of the signaling wave. Another factor which, however, has not been employed for increasing selectivity and eliminating static disturbances is the phase of the signaling wave. While some static disturbances which -may be of substantially the same frequency as the signaling wave may also be substantially in phase therewith, the probabilities are that the greater percentage of static disturbances are out of phase with the signaling wave. If, therefore, a receiving apparatus is constructed which is capable of discriminating between waves differing in phase and of selecting only currents which are in phase with the signaling current a much higher degree of selectivity and freedom from static disturbances may be obtained.

One of the objects of my invention is to provide a simple and eflicient radio apparatus which will have the property of discriminating between currents differing in phase.

It has heretofore been proposed to obtain sharper directivity in reception by employing two or more receiving antennae having different directive properties and by vectorial combination of the currents received upon such a system eliminate reception of interfering signals or strays from certain directions. Another object of my invention 1923. Serial No. 638,362.

is to provide a system in which the receivingapparatus is affected only by currents received by the two or more antennae which are in phase with each other or which bear a predetermined phase relation to each other, whereby a more sharply directive reception may be obtained than when vectorial addition of the currents is employed.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the eppended claims. My invention itself however both as to its organization and method of operation together with further objects and advantages thereof will best be understood by reference to the following description taken in connection with the accompanying drawings in which Figs. 1, 2 and 3 show three different circuit organizations whereby my invention may be carried into effect, and Figs. 4, 5 and 6 are receiving diagrams illustrating the improved directivity in reception which may be obtained with each of the systems of Figs. 1, 2 and 3.

As indicated in the drawings, I preferably employ in my receiving system as a phase selector an electron discharge device 1 of the usual three-electrode type having grid and plate circuits associated therewith. In the arrangement shown in Fig. 1 two unidirectional receiving antennae 2 and 3 are employed which extend in directions approximately 90 from each other. The receiving diagrams of these antennae overlap only to a slight extent, as indicated bv the diagram of Fig. 4, the extent of overlapping being shown by the shaded area of the diagram. If the currents received from-the two antennae were combined vectorially in the ordinary way, three diagrams would result which would have substantially the same shape as the original diagram. It will be possible, however, by the arrangement shown in Fig. 1 to combine the two currents by means of phase selection in such a way that signals will be received only from the directions indicated by the shaded area of the diagram.

In order to secure this desired effect the two antennae 2 and 3 are connected to separate rectifying dectectors 4 and 5, but both of these detectors are controlled by the same local heterodyne source 6 or its equivalent.

If a wave is received from a direction which is not within the overlapping range of the two receiving diagrams, it will act only upon one of the detectors. It will, therefore, affect only the plate circuit or the grid circuit of the phase selector, and neither of these actions will produce any sound in the telephone receiver 7. Upon the other hand, if a signal is received from a direction which is within the range of the overlapping of the directivity diagrams, the signal will act upon both detectors. The phase rotator 8 is so adjusted that signals from the desired direction will produce impulses which are in phase in the grid and plate circuits, and under these circumstances the signals will produce a sound in the telephone receiver. It is apparent that by the means described much sharper direetivity may be obtained than with a simple directive antenna. The arrangement described is, of course, not entirely immune to the effects produced by impulses received from the non-overlapping.

parts of the receiving diagram. If two disturbing impulses are received simultaneously one by one antenna and the other by the other antenna, these two disturbances will act simultaneously upon the grid circuit and the plate circuit of the phase selector. They will, however, produce no effects in the telephone unless they are in phase. Inasmuch as atmospheric disturbances are of indiscriminate phase, it is obvious that the greater part of these simultaneous disturbances will be eliminated. There may, however, be a residual of disturbances which occur simultaneously from different directions and which are in phase, as well as disturbances which come from the same direction as the signaling wave. The effect of these disturbances may be largely overcome by introducing audio tuning 10 in the grid circuit of the system shown in Fig. 1.

The effect of the audio frequency tuning 10 is tointegrate the phase of the current supplied to the grid circuit of device 1. Any wave that does not have a constancy of phase and amplitude or the duration of which is short in comparison with that of the signaling wave will not register in such a way as to form a definite phase. Hence any wave trains impressed upon the plate circuit which are not in phase with the signal will not pro duce any indication unless they are of equal or greater strength than the signal.

The grid of device 1 is preferably given a negative bias by means of the battery 11 as by this means the phase selectivity may be greatly increased.

In the system shown in Fig. 2, a vertical receiving antenna 12 and a loop 13 are provided. It is well known that by veetorial addition of currents received on this combinatlon a receiving diagram of the cardioid shape of A in Fig. 5 is obtained. The loop alone gives a diagram of figure 8 shape, as

indicated by B in Fig. 5. Currents received upon the two collectors are therefore impressed upon the plate circuit of device 1 by means of the coupling transformers 14 and 15, while current from the loop alone is impressed upon the grid circuit of device 1 by means of the coupling transformer 16. Receiving apparatus 17 is coupled to the plate circuit by means of transformer 18.

The receiving diagram which results from this combination is indicated by the shaded arear C of Fig. 5, and it will be noted that it is of quite different shape from the diagram, which would be obtained by veetorial combination. It has its maximum in the direction that the cardioid and Figure 8 have their maximum. In directions 90 from this direction it is zero because the figure 8 is zero and in a direction 180 from its maximum it is zero because the cardioid is zero in that direction. The resulting diagram thus resembles one which would be obtained from a wave antenna one wave length long.

If desired, the method of reception of combining different current effects by a phase selector may be carried still farther by employing two directive systems such as those I have described through a third phase selector, thereby giving still sharper directivity. In Fig. 3 I have indicated a XVZLXG antenna 19 which has a receiving diagram similar to that obtained by the combination of Fig. 2 and a loop 20. Currents received upon the wave antenna 19 are impressed upon the plate circuit of the phase selector and currents received upon the loop are impressed upon the grid circuit. The corresponding reception diagrams are indicated by D and E of Fig. 6.

Assuming that the wave antenna 19 is one Wave length long the signal received and impressed upon the plate circuit ofthe detector-will be in phase with the wa e at the opposite end of the antenna. The signal received on the loop will be 360 out of phase with the signal received from the wave antenna i. e. the two signals will be in phase if the signal comes from the direction of the antenna. If, on the other hand, the signal comes from .a direction which'di'liers about 40 from the length direction of the wave antenna, the signals in the loop and wave antenna will be about 90 out of phase and will produce no indication in the receiving apparatus. Thus a, directivity diagram will be produced similar to that shown by the shaded diagram F of Fig. 6.in which zero reception occurs at about 40 difference in direction from the maximum instead of at 90 difference as in the wave antenna.

While I have shown only three modifications of my invention, it will be apparent that many variations in the apparatus used as well as in the circuit connections employed may be made without departing from the scope of my invention as set forth in the appended claims.

lVhat I claim as new and desire to secure by Letters Patent of the United States, 1s:-

1. The combination in a signal receiving system of two receiving antennae having different directive properties, an electron discharge device, two circuits associated with said device in such a way that the current in one circuit is controlled by the current in the other circuit, means for impressing signaling currents derived from currents -received upon the two antennae upon the two circuits of said device, an indicator associated with one of said circuits and means associated with the second circuit for causing said indicator to respond only to' currents of substantially the same phase as the desired signaling current to be received.

2. The combination in a signal receiving system of two receiving antennae having different directive properties, an electron discharge device, two circuits associated with said device in such a way that the current in one circuit is controlled by the current in the other circuit, means for impressing signaling currents derived from currents received upon the two antennae upon the two circuits of said device, means associated with one of said circuits for maintaining substantially constant the phase of the current thereon, an indicator associated with one of said circuits, and means associated,

with the second circuit for causing said indicator to respond only to currents of substantially the same phase as the desired signaling current to be received.

3. The combination-in a signal receiving system of two receiving antennae having different directive properties, an electron discharge device, two circuits associated with said device in such a way that the current in one circuit is controlled by the current in the other circuit, means for impressing signaling currents derived from currents received upon the two antennae upon the two circuits of said device, one of said circuits comprising a low decrement tuning to the signal frequency, an indicator associated with one of said circuits and means associated with the second circuit for causing said indicator to respond only to currents of substantially the same phase as the desired signaling current to be received.

4. The combination in a signal receiving system 'of two receiving antennae having different directive properties, an electron discharge device, two circuits associated with said device in such a way that the current in one circuit is controlled by the current in the other circuit, means for separately impressing signaling currents derived from currents received upon the two antennae upon the two circuits of said device, means associated with one of said circuits for maintaining substantially constant the phase of the current therein, and an indicator associated with one of said circuits.

5. The combination in a signal receiving system of two receiving antennae having different directive properties, a detector associated with each of said antennae for producing an audio frequency current from the received high frequency current, two separate circuits associated with said detectors, to which the audio frequency currents may be supplied, an indicator associated with one of said circuits, and means associated with the second circuit for causing said indicator to respond only to currents of substantially the same phase as the audio frequency current produced from the desired signalling current to be received.

6. The combination in a signal receiving system of two receiving antennae having different directive properties, a detector associated with each of said antennae for producing an audio frequency current from the received high frequency current, two separate circuits associated with said detectors to which the audio frequency currents may be supplied, means associated with one of said circuits for maintaining substantially constant the phase of the current therein, an indicator associated with one of said circuits, and means associated with the second circuit for causing said indicator to respond only to currents of substantially the same phase as the audio frequency current produced from the desired signaling current to be received.

7 The combination in a signal receiving system of two receiving antennae having different directive properties, a detector associated with each of saidantennae for producing an audio frequency current from the received high frequency current, two separate circuits associated with said detectors to which the audio frequency currents may be supplied, one of said circuits comprising a low decrement tuning for the audio frequency signaling current, an indicator associated with one of said circuits, and means associated with the second circuit for causing said indicator to respond only to currents of substantially the same phase as the audio frequency current produced from the desired signaling current to be received.

8. The combination in a signal receiving system of two receiving antennae having different directive properties, an electron discharge device, two circuits associated with said device in such a way that the current in one circuit is controlled by the current in the other circuit, means for impressing signaling currents derived from currents received upon the two antennae upon the two circuits of said device, an indicator associated with one of said circuits, and means associated with the second circuit for causing said indicator to respond only to currents having a predetermined phase relation to the currents in the second circuit.

9. The combination in a signal receiving system of two receiving antennae having diiferent directive properties, a detector associated witheach of said antennae for producing an audio frequency current from the received high frequency current, two separate circuits associated with said detectors to which the audio frequency currents may be supplied, an indicator associated with one of said circuits, and means associated with the second circuit for causing said indicator to respond only to currents having a predetermined phase relation to the current in the second circuit.

10. The combination in a signal receiving system of an electron discharge device having plate and grid circuits associated therewith, two receiving antennae having different directive properties, means for supplying to one of said circuits, currents derived from signaling currents received upon one of said antenna and means for supplying to the second circuit signaling currents derived from signaling currents received upon the second antenna.

11. The combination in a signal receiving system of an electron discharge device hav lng plate and grid circuits associated therewith, two receiving antennae having different directive properties, means for supplying to one of said circuits currents derived from signaling currents received upon one of said antennae, means for supplying to the second circuit currents derived from signaling currents received upon the second antenna, means associated with one of said circuits for integrating the phase of the current flowing therein, an indicator associated with the plate circuit, and means associated with the grid circuit for causing said indicator to respond only to currents in the plate circuit which are substantially in phase with the current in'the grid circuit.

12. The combination in a signal receiving system of an electron discharge device having plate and grid circuits associated therewith, two receiving antennae having different directive properties, means for sup plying to one of said circuits currents derived from signaling currents received upon one of said antennae, means for supplying to the second circuit currents derived from signaling currents received upon thesecond antenna, one of said circuits comprlsmg a low decrement tuning to the signal frequency, an indicator associated with the plate circuit, and meanis associated with the grid circuit for causing said indicator to respond only to currents in the plate circuit which are substantially in phase with the current in the grid circuit.

13. The combination in a signal rece ving system of an electron discharge devicehaving plate and grid circuits assoclated there with, two receiving antennae havlng dliferent directive properties, means for supplying to one of said circuits currents derlved from signaling currents received upon one of said antennae, means for supplying to the second circuit signaling currents derived from signaling currents received upon the second antenna, means associated with one of said circuits for integrating the phase of the current flowing therein, an indicator associated With the plate circuit, and means associated with the grid circuit for causing said indicator to respond only to currents in the plate circuit which bear a predetermined phase relation to the signal current in the grid circuit. 14. The combination in a signal receiving system of an electron discharge devlce having plate and grid circuits associated there with, two receiving antennae having different directive properties, means for supplying audio frequency signaling currents produced from waves received upon one of sald antenna to one of said circuits, and means for supplying audio frequency signaling currents produced from waves received upon the second antenna to the second circuit.

15. The combination in a signal receiving system of an electron discharge device having plate and grid circuits associated therewith, two receiving antennae having different directive properties, means for supplying to one of said circuits currents derived from signaling'currents received upon one of said antennae, means for supplying to the second circuit currents derived from signaling currents received upon the second antenna, means associated with one of said circuits for integrating the phase of the current flowing therein, an indicator associated wit-h the plate circuit, means associated with the grid circuit for causing said indicator to respond only to currents in the plat-e circuit which are substantially in phase with the current in the grid circuit, and means for adjusting the'phase of the current supplied to one of said circuits.

16. The method of selective reception of radio signals which consists in separately supplying to two circuits currents derived from signaling currents received upon two antennae having different directive properties and controlling the response in an indi cator in one of said circuits by means of current flowing in the second circuit in such a way that the indicator will respond only to currents which are substantially in phase with the desired signaling current in the second circuit.

17. The method of selective reception of radio signals which consists in separately supplying to two circuits currents derived from signaling currents received upon two antennae having different directive properties, integrating the phase of the current flowing in one of said circuits, and controlling the response in an indicator in one of said circuits by means of current flowing in the second circuit in such a way that the indicator will respond only to desired signaling currents which are substantially in phase with the current of integrated phase.

18. The method of selective reception of radio signals which consists in producing audio frequency current from signalingcurrents received upon two antennae havingdifl ferent directive properties, separately jimpressing the audio frequency currents produced upon two different circuits, and controlling the response in an indicator in one of the circuits by means of current flowing in the second circuit in such a way that the indicator will respond only to audio frequency currents which are substantially in phase with'the audio frequency current in the second circuit.

19. The method of selective reception of radio signals which consists in producing audio frequency currents from signaling currents received upon two antennae having different directive properties, separately impressing the audio frequency currents produced upon two different circuits, integrating the phase of the audio frequency current flowing in one of said circuits and controlling the response in an indicator in one of the circuits by means of current flowing inthe second'circuit in such a way that the indicator will respond only to currents which are substantially in phase with the current of integrated phase.

In witness whereof, I have hereunto set my hand this 10th day of May, 1923.

ERNST F. W. ALEXANDERSON. 

